A typical circuit board system comprises a circuit board furnished with electrical components. The circuit board comprises a body made of one or more layers of electrically insulating material and electrical conductors on one or both of the surfaces of the circuit board and/or between the layers of the electrically insulating material. Each of the electrical components can be, for example, an integrated circuit such as a processor or a memory, or a discrete component such as a resistor, a capacitor, an inductor, a transistor, or a diode.
A circuit board system can be subjected to damaging mechanical impacts in many situations. For example, the circuit board system can be a part of a plug-in unit where the circuit board constitutes a body of the plug-in unit and where edges of the circuit board slide in corresponding support elements of a frame or another device for receiving the plug-in unit when the plug-in unit is being installed. If the plug-in unit is being pushed into the frame or the other device in a glancing or otherwise wrong direction, the electrical components of the circuit board system may hit to neighboring plug-in units and/or to structures of the device receiving the plug-in unit.
A known arrangement for protecting electrical components against mechanical impacts comprises a shield plate which is parallel to a circuit board and which is installed to the circuit board with spacers so that there is room for electrical components between the circuit board and the shield plate. An inconveniency related to this protection arrangement is unsuitability for applications where the circuit board system has to be as thin as possible in the direction perpendicular to the circuit board. Furthermore, different thermal expansion coefficients of the circuit board and the shield plate may cause mechanical stresses and/or deformations in the circuit board system.